Detention of stormwater runoff from urban watersheds followed by either infiltration into the ground and/or treatment for quality improvement and beneficial use is becoming increasingly important as stormwater runoff is now considered a valuable water resource and environmental regulations limit the pollutant loads that storm drains can discharge into natural water bodies.
Current art diverts the stormwater runoff to an off-channel detention storage facility for infiltration into the ground and/or treatment for beneficial use. This often requires extensive civil works for the diversion, conveyance, and detention storage facilities and is contingent upon the availability of sufficient land for these facilities. The undertaking is often extensive and cost-prohibitive. One approach for both stormwater diversion and detention is to use inflatable rubber dams across the channel. This approach has limited detention utility because of limited dam height and the sloping nature of the channel, which only enables utilizing half the channel volume in the reach between the rubber dam and the backwater upstream.
Other than the limited in-channel detention storage created by small dams and gates, current art has largely overlooked the potential utility of the stormwater channel for purposes other than conveyance. This is particularly true for the space below the channel, which is only utilized for as the support for the channel bed and banks above. This is an anomaly in urban areas, which normally utilize the space below most facilities as parking structures, shopping centers, sport facilities, etc. Indeed, the space below the channel bed is the ideal location to house a detention storage facility for stormwater runoff, since conveyance to the facility would occur by gravity and there would not be a need for diversion. Depending on the ground formation and environmental suitability, the space below the channel bed may also be suitable for infiltration in addition to detention. The concept eliminates the need for finding a suitable off-channel site for detention, feasible conveyance alignment alternatives, and suitable diversion scheme and would greatly accelerate stormwater conservation while drastically increasing the stormwater protection capability of existing storm drain, since they would also incorporate sizeable detention storage.
Therefore, there is a need for and great benefits from a means of utilizing the vertical space below stormwater channels for stormwater runoff detention and infiltration. This would greatly enhance the utility of the land occupied by or allocated to stormwater channels and provide an effective and simple tool for stormwater management, conservation, water quality enhancement, while increasing the stormwater protection capacity of existing and future stormwater channels.